Methods of separating Pissodes strobi (Peck) from its insect associates in leaders of Picea sitchensis (Bong.) Carr. would enable the associates to be returned to the field when infested leaders are routinely clipped to remove P. strobi. We recently demonstrated a method based on the relative lack of cold-hardiness of P. strobi (Hulme et al. 1986). Another method suggested many years ago (e.g. Taylor 1929) is to exploit the different ability of adult insects to crawl through a screen. To our knowledge the efficacy of such a separation has never been demonstrated. We report here an investigation into the ability of these adult insects to crawl through screens having openings of various sizes, with the objective of establishing how completely these insect associates could be separated from P. strobi